Mechanical Engineering , Industrial. At feet-wide by feet-tall, the Amonix CPV is the largest pedestal-mounted solar panel to be manufactured. The project was particularly challenging because Nectar needed to optimize the design to reduce weight and improve fabrication processes while ensuring that the structure could withstand the extremes of its potential operating environments, which range from dry, hot deserts to cold, windy mountaintops. The MegaModule had to use less material—as well as being easier to manufacture—yet be engineered to last. Trial-and-error prototyping of the massive structure was not an option.
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Credit: Dennis Schroeder. Martha Symko-Davies, a senior supervisor at NREL, says Amonix took the plunge while others balked when NREL offered up its world-record-setting multi-junction cells to industry as a way of trying to slash the cost of solar energy.
Thinking big while focusing on small, a solar company and a national energy lab combined talents to develop a solar power concentrator that generates electricity at prices competitive with natural gas.
Department of Energy's National Renewable Energy Laboratory, is the size of an IMAX screen but costs much less than comparable generators, partly because of the efficiency of its small solar cells.
It delivers more "energy per acre" than anything yet available in the solar energy world. The uses acrylic Fresnel lenses to concentrate sunlight up to times its usual intensity and direct it onto 7, tiny, highly efficient multi-junction PV cells. The cells, originally developed by NREL scientists, can convert Production cells never work quite as well as cells produced in the lab. But the multi-junction cells on the Amonix are achieving 31 percent efficiency at the module level and 27 percent at the system level in the field, the highest ever achieved for an operating CPV concentrator.
That unprecedented efficiency opened the door to reducing costs and reducing land use — both key for solar electricity to reach cost-parity with fossil fuels. A six-inch square silicon wafer in traditional photovoltaic PV panels produces about 2. That same-sized wafer, cut into hundreds of square-centimeter cells in the Amonix , each teamed with a Fresnel lens, produces more than 1, watts. It reduces the required area for cells times. Solar power is at or near price parity in six other states that share California's sunny and dry climates — Arizona, Nevada, Utah, New Mexico, Colorado and Texas.
The also keeps down costs by integrating the lenses, the cells and the mounting structure into a single unit that eliminates most of the parts and costs associated with other concentrator designs. The seven MegaModules that make up the kilowatt system can be hauled on two flatbed trucks, then assembled in the field in hours, rather than weeks.
Those cost-slashing measures, together with the Amonix 's large-scale capacity, are catching the interest of utility companies from California to Colorado. Twenty Amonix s, erected on just five acres of desert, can generate more than a megawatt of rated capacity, enough to power homes.
That's half the space typically needed to generate that much power. The key breakthrough that lifted the to a 50 percent greater power output than previous generations of Amonix generators was the substitution of the multi-junction cells made of gallium indium arsenide and gallium phosphide for the more common silicon cells.
Cells made from gallium, indium and other elements from the III and V columns of the periodic table are more expensive to produce today, but also can be more efficient at converting the sun's photons into usable electrons for electricity.
NREL scientists had developed a high-efficiency multi-junction indium gallium phosphide PV cell that had been used previously for energy for spacecraft. To offer up the more efficient multi-junction cell as a possible replacement for the silicon cells used in most PV concentrators, NREL issued a request for proposals for projects designed to accelerate multi-junction cell development and their integration into CPV solar systems.
At the end of the NREL project, Amonix was able to demonstrate close to 31 percent efficiency for a one-square-meter module — a world record at the time. Martha Symko-Davies, a senior supervisor at NREL, recalled that most concentrator companies could not see the benefits of switching to new-generation solar cells, but Amonix was different, conducting research and development with NREL to overcome stiff challenges.
A conundrum was how to use the highly efficient cells without breaking the bank. The power amplification of the Fresnel lens allowed the solar cells to be tiny — thus a small fraction of the cost of bigger cells — while still packing record-setting efficiency. Researchers developed a new receiver package of cells and lenses to ensure that the cells would not short out. They solved the distortion problem that happens when a lens doesn't focus all colors on the same convergence point.
And they overcame the thermal issues that crop up when a cell has to handle the intensity of suns. Solar energy has found a niche on rooftops, especially of green-minded homeowners. But if it is to play a major role in the broader electricity market, it needs to come in at or below the costs of electricity generated from coal, which is projected to cost from 6 cents to 15 cents per kilowatt-hour in four years.
The 's cost per kilowatt-hour is expected to be well within those price ranges as production and sales continue to grow. The 's two-axis tracker can be repositioned throughout the day to follow the sun, but also can be re-positioned to shield the cells from extreme wind, increasing the life of the system. It allows the cells to capture sunlight for a longer time throughout the day and through all seasons of the year.
Field tests indicate that depending on the location, the two-axis tracker captures up to 50 percent more energy than fixed one-axis systems. Utilities expect their generators to last 50 years. The Amonix can reach that target with proper maintenance and timely replacement of certain parts, said a spokesman for the company. The two-axis tracker is the only moving component on Amonix's CPV systems and has been designed for reliability and minimum maintenance.
The energy needed to move the two-axis tracker amounts to less than 1 percent of the power output. The system has just 12 subassemblies, which are shipped to installation sites for deployment. Once the site is ready, an Amonix system can be installed very quickly, within hours. By contrast, some systems require shipment of thousands of parts to the installation site.
Cost savings were factored in every step of the way — from foundry to grid — said Bob McConnell, who worked at NREL before he left the lab in to join Amonix and help bring the research to market. The result is a generator manufactured at about a third to one half of generators using crystalline silicon or thin-film approaches. Multi-junction cells can operate at higher ambient temperatures than traditional PV cells, making them ideal for sunny and dry climates in the southwestern United States, and ripe for future cost reductions.
The concentrator also is kinder to the environment than most large systems, using no water in its operation. Propped up two feet above the land, it doesn't hinder the movement of wildlife.
Credit: Dennis Schroeder Enlarge image Martha Symko-Davies, a senior supervisor at NREL, says Amonix took the plunge while others balked when NREL offered up its world-record-setting multi-junction cells to industry as a way of trying to slash the cost of solar energy.
Credit: Dennis Schroeder. Martha Symko-Davies, a senior supervisor at NREL, says Amonix took the plunge while others balked when NREL offered up its world-record-setting multi-junction cells to industry as a way of trying to slash the cost of solar energy. Thinking big while focusing on small, a solar company and a national energy lab combined talents to develop a solar power concentrator that generates electricity at prices competitive with natural gas. Department of Energy's National Renewable Energy Laboratory, is the size of an IMAX screen but costs much less than comparable generators, partly because of the efficiency of its small solar cells. It delivers more "energy per acre" than anything yet available in the solar energy world.
Super-Efficient Cells Key to Low-Cost Solar Power
Amonix, Inc. The company manufactures concentrator photovoltaic CPV products designed for installation in sunny and dry climates. CPV products convert sunlight into electrical energy in the same way that conventional solar photovoltaic technology does, except that they use optics to focus the solar radiation before the light is absorbed by solar cells. According to a comparative study of energy production of solar technologies, CPV systems require no water for energy production and produce more energy per megawatt MW installed than traditional PV systems. In May , the Alamosa Solar Generating project, owned and operated by Cogentrix Energy, began commercial operation. This is the largest CPV power plant in the world and is expected to produce enough clean renewable energy per year to power more than 6, homes and will avoid the emissions of over 43, metric tons of carbon dioxide per year. The Alamosa Solar Generating Project is supported by a power purchase agreement PPA , which is a long-term agreement to sell the power it will generate.